This invention relates to a work cylinder having an internally-disposed drain valve and, more particularly, such a cylinder and drain valve configuration where the cylinder is located at a distance from the compressor, reservoir, and drain valve associated with these two devices. An application of such a cylinder, drain valve configuration, located at a distance from the compressor and reservoir, would be that of a railroad situation where a railroad car on which the cylinder is mounted is distant from the locomotive on which the compressor is located. The locomotive also contains the main reservoir which typically has a separate drain valve associated therewith. As compressed air travels from the main reservoir to the distant cars, it further cools and, consequently, more water vapor in the air liquidates. This problem becomes further complicated due to the water causing corrosion, or possibly freezing within the cylinder itself. Moreover, it is not practical to provide an additional drain valve at each car, due to the expense involved in the additional maintenance and installation costs, and the space-constraints that the additional elements would operate under. Adding a separate drain valve to each car further entails the addition of the necessary piping to connect these drain valves to the system, further increasing installation and maintenance costs.
The cylinder location in railroad-type applications further makes the use of a separate drain valve in conjunction with the cylinder impractical, since the cylinder can be the lowest point in the car; and, since the drain valve in a number of instances, would be secured to the car, the valve would be higher than the cylinder and could not effect a draining operation with respect to this lower-disposed cylinder. Furthermore, due to the size of the cylinder, the cylinder itself can act as a reservoir in and of itself, thereby resulting in an increased amount of condensation occurring within the cylinder.